Table of Contents
Chapter 2 MCQs in English; Sorting Materials into Groups
1. On what does the selection of a material for making an object depend?
I. On the basis of the properties of the material
II. On the basis of the use of the material
Code:
Answer: A
The correct answer is both I and II.
Every object we see around us is made of one or another material. The selection of a material for making any object is done carefully. This selection mainly depends on the properties of the material and its intended use.
First, the physical and chemical properties of the material are considered. If a strong object has to be made, a material with greater hardness and strength is selected. If the object has to be lightweight, a material with low density is chosen. Similarly, if the object has to withstand heat, a heat-resistant material is selected, and if it has to conduct electricity, a good electrical conductor is chosen.
The second important basis is the purpose of use of the object. For example, copper is used for making electrical wires because it is an excellent conductor of electricity. Aluminium or stainless steel is commonly used for kitchen utensils because they are good conductors of heat and are comparatively durable. The handle of a hammer is made of wood or fibre so that electricity or excessive heat does not reach the hand.
If a raincoat is to be made, a waterproof material is selected, whereas soft and comfortable fibres are used for making clothes.
Thus, both the properties of the material and its use are equally important in the manufacture of any object.
Source: NCERT Science Class 6 Chapter 2, Page No. 12
2. Which of the following are materials?
Answer: D
The correct answer is All of the above.
Every object around us is made of one or more materials. Materials are the basic substances used to make different objects.
Glass is used for making windows, bottles, bulbs, and laboratory apparatus.
Metals such as iron, copper, aluminium, gold, and silver are used to make many objects because of their strength, lustre, and conductivity.
Plastic is a lightweight, waterproof, and easily mouldable material. It is used to make buckets, bottles, toys, pipes, and many parts of electrical appliances.
Wood is used for making furniture, doors, windows, paper, and many household items.
Cotton is used to make clothes, bandages, and mattresses. Besides these, paper, clay, and leather are also important materials used to make many useful objects.
A single object may also be made of several materials. For example, a school bag may contain cloth, plastic, metal, and foam.
Therefore, all the given options are examples of materials.
Source: NCERT Science Class 6 Chapter 2, Page No. 13
3. Which of the following is a lustrous material?
Answer: A
The correct answer is Gold.
The property of a material by which it reflects light and appears shiny is called lustre. Materials having this property are called lustrous or shiny materials.
Gold is a precious metal with a very high natural shine. This is why it has been used since ancient times for making jewellery, coins, and decorative items. Gold does not rust under normal conditions, so its shine remains for a long time.
Most metals, such as iron, copper, aluminium, and silver, appear shiny when freshly cut. Over time, when exposed to air and moisture, some metals form an oxide layer on their surface, causing their shine to decrease.
Why are the other options incorrect?
Rubber is a non-metallic material and is generally not lustrous.
Chalk has a rough and dull surface.
A book is not a material itself but an object made of different materials, mainly paper.
Thus, the identifying feature of lustrous materials is their ability to reflect light.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
4. What is the meaning of ‘Lustrous’?
Answer: C
The correct answer is Shiny.
The word lustrous means shiny or having lustre. When light falls on the surface of a material and it reflects the light well, the material appears shiny.
This property is especially found in metals. Metals such as gold, silver, copper, aluminium, and iron appear highly shiny when freshly cut or polished. Because of this property, metals are used for making jewellery, decorative items, utensils, and machines.
It is important to note that not all shiny materials are metals, and not all non-metals are completely non-lustrous. However, generally, the most common characteristic of metals is that they are lustrous.
Why are the other options incorrect?
Hardness is the property of a material to resist pressure or scratching.
Soft materials can be pressed or bent easily.
Transparent materials allow light to pass through them almost completely, such as clear glass.
Thus, the correct meaning of lustrous is shiny.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
5. What are hard materials?
Answer: C
The correct answer is Option (C).
Hardness is one of the physical properties of a material that determines how difficult it is to press, compress, or scratch. If a material does not change its shape easily when pressed by hand or scratched with another object, it is called a hard material.
For example, wood, stone, iron, steel, aluminium, and glass are comparatively hard materials. It is almost impossible to change their shape by pressing them with the hand, and they cannot be scratched easily.
On the other hand, cotton, sponge, wax, clay, and rubber are comparatively soft materials. Their shape changes easily when pressed by hand, and they can often be scratched easily.
It is important to note that hardness and strength are not the same property. A material may be hard but can still break when subjected to a strong impact. For example, glass is hard but also brittle. On the other hand, rubber is comparatively soft but does not break easily.
Analysis of the options:
Option (A) is correct because hard materials are difficult to press.
Option (B) is also correct because being difficult to compress is a characteristic of hard materials.
Therefore, Option (C) is the correct answer.
Option (D) is incorrect.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
6. Which of the following is not a metal?
Answer: B
The correct answer is Wood.
Metals are materials that generally possess properties such as lustre, hardness, malleability, ductility, and good thermal and electrical conductivity. Most metals exist in the solid state at room temperature.
Iron, gold, and silver are all common examples of metals.
Iron is used for making buildings, bridges, machines, and industrial equipment.
Gold is a precious metal mainly used in jewellery and electronic devices.
Silver is an excellent conductor of electricity and is used in jewellery as well as scientific instruments.
Wood is not a metal. It is a natural material obtained from plants and is mainly composed of cellulose and lignin. Wood is a poor conductor of electricity and does not possess metallic properties such as lustre or ductility.
It is also important to note that some metals lose their shine over time when exposed to air and moisture. For example, iron develops rust and copper develops a green coating, whereas gold generally retains its shine for a long time under normal conditions.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
7. Identify the incorrect statement from the following:
Answer: C
The correct answer is Option (C) because it is the incorrect statement.
The first statement is correct. Materials that are difficult to press or compress are called hard materials, for example, wood, stone, and iron.
The second statement is also correct. Materials that can be pressed or scratched easily are called soft materials, such as cotton, sponge, wax, and clay.
The third statement is incorrect. It is not scientifically correct to say that metals always remain shiny. Most metals are shiny initially, but over time, when exposed to air, moisture, and other chemicals, a layer of oxide or other compounds forms on their surface, reducing their shine.
For example:
Iron develops rust (Iron Oxide).
Copper develops a green coating (Copper Carbonate).
Silver may develop a black coating (Silver Sulphide).
Therefore, NCERT states that the true lustre of metals is usually seen more clearly on a freshly cut surface.
Option (D) is incorrect because the first and second statements are correct.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
8. What is the meaning of the term ‘Insoluble’?
Answer: A
The correct answer is Not soluble.
When a substance is mixed with a liquid such as water, two situations are possible.
If the substance dissolves completely in water to form a uniform mixture, it is called soluble. For example, sugar and salt dissolve easily in water.
On the other hand, if a substance does not dissolve in water even after stirring or mixing for a long time, it is called insoluble.
Sand, chalk powder, sawdust, stones, and oil (although it forms a separate layer) do not dissolve in water; therefore, they are considered insoluble in water.
It is important to note that insoluble and immiscible are different terms.
Soluble/Insoluble are generally used for the dissolving or non-dissolving of solids in water.
Miscible/Immiscible are mainly used for whether two liquids mix with each other or not. For example, oil and water are immiscible.
Why are the other options incorrect?
Unmixed means not mixed.
Opaque refers to a material through which light cannot pass.
Transparent refers to a material through which light passes almost completely.
Therefore, the correct meaning of insoluble is not soluble.
Source: NCERT Science Class 6 Chapter 2, Page No. 15
9. Choose the correct statement regarding an insoluble substance.
Answer: C
The correct answer is Option (C).
Insoluble substances are those that do not dissolve in a solvent such as water. Even if such substances are stirred for a long time, they do not dissolve in water. They either settle at the bottom of the container or float on the surface. Thus, they do not form a uniform solution with water.
In contrast, substances that dissolve completely in water to form a uniform mixture are called soluble substances. For example, salt, sugar, and alum dissolve easily in water, whereas sand, chalk powder, sawdust, and stone powder do not dissolve in water and are therefore called insoluble substances.
It is also important to understand that a substance not dissolving in water and a substance floating or sinking in water are different properties. For example, sawdust floats on water while sand settles at the bottom, but both are insoluble in water.
Analysis of the options:
Option (A) is incorrect because insoluble substances do not dissolve easily in water.
Option (B) is also incorrect because they do not dissolve even after prolonged stirring.
Therefore, Option (C) is the correct answer.
Source: NCERT Science Class 6 Chapter 2, Page No. 15
10. Which of the following are examples of soluble substances?
Answer: D
The correct answer is Option (D).
Soluble substances are substances that dissolve in water to form a uniform solution. After dissolving, their particles spread evenly throughout the water and cannot be seen separately.
Salt (Sodium Chloride) dissolves easily in water. After dissolving, its ions spread throughout the water. This is why seawater contains a large amount of dissolved salt.
Sugar (Sucrose) also dissolves completely in water. Because of this property, it is widely used in tea, sherbets, sweets, and other beverages.
Washing powder also generally dissolves in water and forms a solution that helps in cleaning clothes. The surfactants present in it play an important role in removing dirt and grease.
In contrast, substances such as sand, chalk powder, sawdust, and soil do not dissolve in water and are called insoluble substances.
The solubility of a substance in water depends on factors such as temperature, the nature of the substance, and the properties of the solvent. For example, most solid substances dissolve in greater quantities in hot water than in cold water.
Source: NCERT Science Class 6 Chapter 2, Page No. 15
11. Consider the following statements:
I. All liquids are miscible with water.
II. Gases are soluble in water to a small extent.
Which of the above statement(s) is incorrect?
Answer: A
The correct answer is Only I.
Let us analyse both statements separately.
Statement I: “All liquids are miscible with water.”
This statement is incorrect. Not all liquids mix with water. Some liquids mix completely with water, while others form a separate layer.
For example, alcohol, vinegar, and glycerine are completely miscible with water, whereas kerosene, mustard oil, coconut oil, and other edible oils do not mix with water and form a separate layer after some time. Therefore, it is scientifically incorrect to say that all liquids are miscible with water.
Statement II: “Gases are soluble in water to a small extent.”
This statement is correct. Many gases dissolve in water in limited quantities. For example, oxygen and carbon dioxide dissolve slightly in water. Dissolved oxygen is essential for the respiration of fish and other aquatic organisms. A decrease in the amount of dissolved oxygen can adversely affect aquatic life.
Thus, the first statement is incorrect, while the second statement is correct. Therefore, the correct answer is Only I.
Source: NCERT Science Class 6 Chapter 2, Page No. 15
12. Which of the following options is correct?
I. Kerosene oil is soluble in water.
II. Honey is soluble in water.
Answer: C
The correct answer is Option (C).
The first statement is incorrect. Kerosene oil is not soluble in water. It does not form a uniform mixture with water but floats on its surface as a separate layer. This is because water is a polar liquid, whereas kerosene is a non-polar liquid. Polar and non-polar substances generally do not dissolve in each other.
The second statement is correct. Honey mainly consists of sugars such as glucose and fructose, which are soluble in water. Therefore, honey gradually dissolves completely when mixed with water. It dissolves even faster in lukewarm water.
It is also important to understand that solubility and floating or sinking are different physical properties. Honey may initially sink because of its higher density, but it eventually dissolves in water to form a solution. Kerosene, on the other hand, floats on water but does not dissolve in it.
Similarly, the formation of separate layers by oil and water is an example of immiscible liquids.
Source: NCERT Science Class 6 Chapter 2, Page No. 16
13. Which of the following statements is incorrect?
I. Mustard oil is soluble in water.
II. Lemon juice is insoluble in water.
Answer: B
The correct answer is Option (B) because both statements are incorrect.
Statement I: “Mustard oil is soluble in water.”
This statement is incorrect. Mustard oil is not soluble in water. Even after stirring, it does not form a uniform mixture with water. After some time, it appears as a separate layer on the surface. This is because water is a polar liquid, whereas oil is non-polar. Polar and non-polar substances generally do not dissolve in each other.
Statement II: “Lemon juice is insoluble in water.”
This statement is also incorrect. Lemon juice dissolves completely in water and forms a uniform solution. That is why beverages such as lemonade and shikanji can be prepared easily. The presence of citric acid and other water-soluble substances makes lemon juice soluble in water.
Similarly, vinegar is also soluble in water, whereas mustard oil, coconut oil, and kerosene are insoluble in water.
This question also highlights that substances are classified as soluble or insoluble based on their ability to dissolve in water.
Source: NCERT Science Class 6 Chapter 2, Page No. 16
14. Which of the following statements is incorrect?
Answer: A
The correct answer is Option (A).
Transparency is an important optical property of materials. Based on this property, materials are classified as transparent, translucent, and opaque.
Transparent materials allow almost all light to pass through them. Therefore, objects behind them can be seen clearly. Examples include clear glass, pure water, air, and some transparent plastics.
Opaque materials do not allow light to pass through them. As a result, objects behind them cannot be seen. Wood, bricks, stones, metals, and walls are common examples.
Translucent materials allow only part of the light to pass through them. Objects behind such materials can be seen but not clearly. Frosted glass, butter paper, and some thin plastic sheets are examples.
Analysis of the options:
Option (A) is incorrect because materials through which objects can be seen are called transparent, not opaque.
Option (B) is correct.
Option (C) is correct because wood does not allow light to pass through it.
Option (D) is also correct.
Source: NCERT Science Class 6 Chapter 2, Page No. 16
15. Materials through which objects can be seen clearly are called:
Answer: C
The correct answer is Option (C) – Transparent.
Transparent materials allow almost all light to pass through them. As a result, objects behind them can be seen clearly without any obstruction.
Examples of transparent materials include clear glass, pure water, air, and certain transparent plastics. This is why glass is commonly used in windows, allowing both light to enter and a clear view of the outside.
In contrast, translucent materials allow only part of the light to pass through them. Objects behind such materials appear blurred. Frosted glass and butter paper are common examples.
Opaque materials do not allow light to pass through them at all. Therefore, objects behind them cannot be seen. Wood, metals, stones, and walls are examples of opaque materials.
The property of transparency is an important factor in selecting materials for different purposes. For example, laboratory beakers, bottles, and many scientific instruments are made of glass so that the processes taking place inside can be observed easily.
Source: NCERT Science Class 6 Chapter 2, Page No. 16
16. Which of the following is not a translucent material?
Answer: A
The correct answer is Option (A).
Translucent materials allow only a part of the light to pass through them. Objects placed behind such materials can be seen, but not clearly. These materials are neither completely transparent nor completely opaque.
Oiled paper, frosted glass, and in many cases muddy or turbid water behave as translucent materials because the light passing through them gets scattered. As a result, objects behind them appear blurred.
In contrast, thick wood does not allow light to pass through it at all. Therefore, it is an opaque material, not a translucent one. Objects placed behind wood cannot be seen.
Materials are classified according to the amount of light they allow to pass through:
Transparent → Allow almost all light to pass through.
Translucent → Allow only some light to pass through.
Opaque → Do not allow light to pass through.
This principle is applied in making window panes, frosted bathroom glass, laboratory equipment, and many scientific instruments.
Source: NCERT Science Class 6 Chapter 2, Page No. 16
17. Butter paper is:
Answer: B
The correct answer is Option (B) – Translucent.
Butter paper is a translucent material. It allows only a part of the light to pass through it. Therefore, objects behind it can be seen, but they do not appear clearly. This property distinguishes it from transparent and opaque materials.
Transparent materials, such as clear glass, pure water, and air, allow almost all light to pass through them. Hence, objects behind them are seen clearly.
On the other hand, opaque materials, such as wood, metals, stones, and walls, do not allow light to pass through them. Therefore, objects behind them cannot be seen.
Translucent materials fall between these two categories. They allow only some light to pass through while scattering the rest. As a result, objects behind them appear blurred. Butter paper, frosted glass, oiled paper, and certain thin plastic sheets are common examples.
NCERT demonstrates this concept through a simple activity. When cooking oil or butter is applied to an ordinary sheet of paper, the oily portion allows more light to pass through than the untreated part. A bulb can be seen through that portion, but not clearly. This explains why butter paper is translucent.
Butter paper is commonly used for packaging bakery products, baking cakes and biscuits, preventing food from sticking, and wrapping food items. Due to its translucent nature, the outline of the packed object is visible but not clearly.
Analysis of the other options:
Option (A) is incorrect because objects cannot be seen clearly through butter paper.
Option (C) is incorrect because butter paper does not block all light.
Option (D) is also incorrect.
Source: NCERT Science Class 6 Chapter 2, Page No. 17
18. Consider the following statements:
Most metals appear shiny when freshly cut.
All metals retain their shine throughout their lifetime.
Some metals lose their shine when exposed to air and moisture.
Choose the correct answer using the code given below:
Answer: C
Statement 1 is correct. One of the important physical properties of metals is lustre. When the surface of a metal is freshly cut, polished, or rubbed, it reflects light well and appears shiny. Gold, silver, copper, and aluminium are common examples.
Statement 2 is incorrect. It is not scientifically correct to say that all metals remain shiny forever. Many metals react with air, moisture, or other chemicals and form a layer of oxides or other compounds on their surface, causing them to lose their shine. For example, iron forms rust (iron oxide), while copper develops a green coating (copper carbonate). However, metals like gold retain their shine for a long time under normal conditions.
Statement 3 is correct. The lustre of many metals gradually decreases due to exposure to the atmosphere. Therefore, metals are often polished or coated with paint or other protective layers to reduce corrosion.
Hence, only statements 1 and 3 are correct.
Source: NCERT Science Class 6 Chapter 2, Page No. 14
19. A substance settles at the bottom when added to water but does not dissolve in it. Which of the following statements is correct?
Answer: C
The ability of a substance to dissolve in water (solubility) and its tendency to sink or float are two different physical properties. Students often confuse these two concepts, but they are not the same.
If a substance settles at the bottom of water, it only indicates that its density is greater than that of water. It does not mean that the substance will dissolve in water. For example, sand settles at the bottom but does not dissolve in water. Therefore, sand is an insoluble substance.
Similarly, substances such as sawdust float on the surface of water but still do not dissolve. Thus, floating or sinking does not determine whether a substance is soluble or insoluble.
The other options are incorrect because a substance that settles at the bottom is not necessarily soluble, transparent, or a metal.
Hence, the correct answer is Option (C).
Source: NCERT Science Class 6 Chapter 2, Page No. 15
20. Match the following:
Code:
Answer: A
Materials are classified according to the extent to which they allow light to pass through them.
Transparent materials, such as clear glass and pure water, allow almost all light to pass through them. Therefore, objects behind them can be seen clearly. Hence, A-2 is correct.
Translucent materials, such as frosted glass, butter paper, and oiled paper, allow only some light to pass through. Objects behind them can be seen, but not clearly. Hence, B-1 is correct.
Opaque materials, such as wood, bricks, metals, and stones, do not allow light to pass through them. Therefore, objects behind them cannot be seen. Hence, C-3 is correct.
Thus, the correct matching is A-2, B-1, C-3.
Source: NCERT Science Class 6 Chapter 2, Page No. 16–17
21. Which of the following options contains substances that all form a homogeneous solution with water?
Answer: A
A substance that dissolves completely in water to form a homogeneous solution is called a soluble substance.
Salt, sugar and honey are all soluble in water. Salt dissolves in the form of ions, while the sugars present in sugar and honey disperse uniformly throughout the water. As a result, they form a homogeneous solution in which no separate particles are visible.
Option B is incorrect because kerosene, mustard oil and coconut oil do not dissolve in water. They form a separate layer and exhibit immiscible behaviour.
Option C is also incorrect because sand, chalk powder and sawdust are insoluble in water. Some settle at the bottom while others float on the surface, but none of them dissolve.
Option D is incorrect because although salt dissolves in water, mustard oil and sand do not.
It is important to remember that solubility, floating or sinking, and miscibility are three different physical properties. Competitive examinations frequently include questions based on the differences between these concepts.
Source: NCERT Science Class 6, Chapter 2, Page No. 15–16
22. Consider the following statements:
Transparent materials allow almost all light to pass through them.
Objects can be seen clearly through translucent materials.
Opaque materials do not allow light to pass through them.
Choose the correct answer using the code given below:
Answer: B
Statement 1 is correct. Transparent materials allow almost all light to pass through them. Therefore, objects behind them can be seen clearly. Clear glass, pure water and air are common examples. This is why transparent glass is widely used in windows and scientific instruments.
Statement 2 is incorrect. Translucent materials allow only a part of the light to pass through them. As a result, objects behind them are visible but not clearly. Frosted glass, butter paper and oiled paper are common examples.
Statement 3 is correct. Opaque materials do not allow light to pass through them. Therefore, objects behind them cannot be seen. Wood, metals, bricks and stones are common examples.
This classification is based on the transmission of light through materials. Questions based on the properties and examples of transparent, translucent and opaque materials are commonly asked in competitive examinations.
Source: NCERT Science Class 6, Chapter 2, Page No. 16–17
23. Which of the following materials would be most suitable for making a window through which the outside view is clearly visible while allowing sufficient light to enter?
Answer: C
If the purpose of a window is to allow sufficient light into a room while providing a clear view of the outside, a transparent material should be selected. Clear glass allows almost all light to pass through it, making objects behind it clearly visible.
For this reason, most windows in houses, schools, offices and vehicles are made of clear glass. It allows natural light to enter while providing an unobstructed view of the surroundings.
The other options are not suitable. Frosted glass is translucent, so objects appear blurred through it. It is generally used in bathrooms and places where privacy is required. Thick wood and cardboard are opaque materials that do not allow light to pass through.
Therefore, wherever both clear visibility and adequate light are required, clear glass is the most suitable material.
Source: NCERT Science Class 6, Chapter 2, Page No. 16
24. Match the following:
Code:
Answer: A
Materials are classified into three major categories based on the transmission of light.
Transparent materials allow almost all light to pass through them. Therefore, clear glass is an example of a transparent material. Hence, A-2 is correct.
Translucent materials allow only a part of the light to pass through them. Objects behind them cannot be seen clearly. Butter paper is a common example. Hence, B-3 is correct.
Opaque materials do not allow light to pass through them. Wood blocks light completely and is therefore an opaque material. Hence, C-1 is correct.
Thus, the correct matching is A-2, B-3, C-1.
Source: NCERT Science Class 6, Chapter 2, Page No. 16–17
25. Which of the following statements about the transparency of materials is correct?
Answer: C
Transparency is an important optical property of materials. It determines how much light a material allows to pass through it.
If a material allows almost all light to pass through, it is called transparent. If it allows only a part of the light to pass through, it is called translucent. If it does not allow light to pass through at all, it is called opaque.
The other options are incorrect. Objects cannot be seen clearly through translucent materials. Opaque materials do not allow light to pass through them. It is also incorrect to say that only metals can be transparent. In fact, most metals are opaque, whereas clear glass, water and air are common examples of transparent materials.
Thus, the classification of materials is based on the transmission of light, which is one of the key scientific concepts explained in this chapter.
Source: NCERT Science Class 6, Chapter 2, Page No. 16–17